1. Field of the Invention
The present invention relates generally to wheeled carts and, more particularly, to wheeled carts having a ladder function.
2. Description of the Prior Art
Generally, carts are wheeled structures that are used for transporting loads. Also, generally, ladders are structures that can be climbed to enable a person to change the elevation of one's position. Throughout the years, a number of innovations have been developed relating to combined carts and ladders, and the following U.S. Pat. Nos. are representative of some of those innovations: 3,857,460; 5,082,086; 5,314,042; and 5,295,556. More specifically, U.S. Pat. No. 3,857,460 discloses a combination ladder and tool cart in which the cart portion and the ladder portion are separate and distinct structures. For purposes of economy and convenience, it would be desirable if a combination cart and ladder had a ladder portion that serves as both a ladder and a cart.
U.S. Pat. No. 5,082,086 discloses a wheeled ladder whose ladder portion is not extensible. To accommodate a wide variety of heights, it would be desirable if a combination cart and ladder had an extensible ladder portion.
U.S. Pat. No. 5,314,042 discloses a combination cart and ladder which is in the form of a tree stand and transport vehicle. The ladder is extensible, and the wheels are at a fixed location at one end of the ladder. When the ladder portion is used as a cart and a load is placed on the ladder portion, the load is pulled by a user. It is noted that pulling a load is facilitated if the composite center of gravity of the load and the combination cart and ladder is located near the cart wheels so that the load can be nearly balanced over the wheels. However, with the wheels being at a fixed location at one end of the ladder, it is difficult for the composite center of gravity of the load and the combination cart and ladder to be located near the cart wheels. In this respect, it would be desirable if a combination cart and ladder were provided with wheels that can be adjustably positioned along the length of the ladder portion so that the composite center of gravity of the load and the combination cart and ladder can be located near the cart wheels in order to nearly balance the load over the wheels.
U.S. Pat. No. 5,295,556 discloses a multipurpose hunting cart which includes a nonextensible ladder portion. In addition, this patent discloses a platform portion that is oriented with respect to the ladder portion at a fixed, obtuse orientation. As a result of this fixed, obtusely oriented platform, the platform portion constantly sticks out from the ladder portion. To avoid this result, it would be desirable if a combination cart and ladder were provided with a platform portion that does not constantly stick out from the ladder portion.
U.S. Pat. Nos. 4,991,690 and 5,080,193 may be of interest for their disclosure of hunters' ladders that are designed to be fixed to trees.
Still other features would be desirable in a ladder-based cart apparatus. As discussed above, when a combination cart and ladder is used as a cart, it would be desirable for the wheels to be adjustable so that a load could be nearly balanced over the wheels. However, when the combination cart and ladder is used as a ladder, it would be desirable if the wheels were not in contact with the ground at all. When wheels are in contact with the ground, but the wheels are not supposed to roll, the wheels must be supplied with brakes to prevent rolling. By avoiding contact of the wheels with the ground when the combination cart and ladder is used as a ladder, there is no need for brakes for the wheels.
When the combination cart and ladder is used to provide an elevated platform in a tree, it would be desirable for a way to be provided to secure the combination cart and ladder and the elevated platform to the tree. When the combination cart and ladder is used as a cart, it would be desirable for a handle to be provided for controlling the cart operation.
Thus, while the foregoing body of prior art indicates it to be well known to use combination carts and ladders, the prior art described above does not teach or suggest a ladder-based cart apparatus which has the following combination of desirable features: (1) has a ladder portion that serves as both a ladder and a cart; (2) has an extensible ladder portion; (3) provides wheel that can be adjustably positioned along the length of the ladder portion so that a composite center of gravity of a load and the combination cart and ladder can be located near the cart wheels in order to nearly balance the load over the wheels; (4) provides a platform portion that does not constantly stick out from the ladder portion; (5) provides wheels that can be adjusted so that they are not in contact with the ground at all when the device is in a ladder mode; (6) does not need wheel brakes; (7) provides a way to secure the combination cart and ladder and an elevated platform to a tree; and (8) provides a handle for controlling the cart operation. The foregoing desired characteristics are provided by the unique ladder-based cart apparatus of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.